[luatex] Three questions about tex.print("a\nb\n\nc")

[Eduardo Ochs]

Hi list,

consider the following code:

--snip--snip--
rm -Rfv /tmp/test/
mkdir   /tmp/test/
cd      /tmp/test/
cat > abc.lua <<'%%%'
  tex.print("a\nb\n\nc")
%%%
cat > test.tex <<'%%%'
  \par a
       b

       c                                             % a b \par c
  \par                  \directlua{dofile "abc.lua"} % aObOOc
  \par \catcode`\^^J=10 \directlua{dofile "abc.lua"} % a b c
  \par \catcode`\^^J=14 \directlua{dofile "abc.lua"} % a
  \par \catcode`\^^J=5  \directlua{dofile "abc.lua"} % a
  \bye
%%%
luatex test.tex
xpdf   test.pdf
--snip--snip--

When I started using "tex.print" years ago I expected that in

  tex.print("a\nb\n\nc")

the first "\n" would be translated to a space and the "\n\n" between
"b" and "c" would be translated to a \par. I wasn't so, but I tried
this:

  \catcode`\^^J=10

and I thought that that would fix everything. But I just discovered
that the "\n\n" gets translated to a space, and I checked on p.37 of
the TeXBook and category 10 is "space" (duh!!!), and that's why the
result of the

  \par \catcode`\^^J=10 \directlua{dofile "abc.lua"} % a b c

in the .tex file above is "a b c" in a single line. The obvious fix
would be to use \catcode`\^^J=5 - category 5 is "end of line" - but
the output of these two lines in my .tex file

  \par \catcode`\^^J=14 \directlua{dofile "abc.lua"} % a
  \par \catcode`\^^J=5  \directlua{dofile "abc.lua"} % a

is the same... just an "a", and the rest disappears. So apparently
\catcode`\^^J=5 is behaving just like \catcode`\^^J=14, where category
14 is "comment character". So...

  Question 1: how do I make "\n"s in tex.print behave like "return"s?
  Question 2: how do I get the catecode of "\n" from Lua?
  Question 3: how do I set the catecode of "\n" from Lua?

    Thanks in advance...
    Eduardo Ochs
    http://anggtwu.net/dednat6.html
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